Congress enacted the Clean Water Act (CWA) to create a federal system for pollution control. But Congress wanted that federal system to leave room for the states as well. That’s why the CWA encourages “cooperative federalism” between federal and state enforcement. Under the CWA, states can create their own water quality standards, as long as these meet federal requirements. The same is true for permitting regimes. And states are free to create their own administrative procedures for handling CWA violations.

In addition to federal and state enforcement, the CWA also permits private citizens to sue to enforce the CWA in certain circumstances. But such suits are blocked, or “precluded,” against a particular defendant if a state has initiated an enforcement proceeding against that same defendant and if that enforcement proceeding meets certain standards. For a state proceeding to preclude citizen suits, the state must be “diligently prosecuting” an action “comparable” to the federal proceeding prescribed in the CWA for federal violations. Fitting with the theme of cooperative federalism, the state proceeding does not need to mimic the federal one exactly; it must only be “comparable.”

Dakota Finance, doing business as Arabella Farms, is a family-owned South Carolina working farm. While preparing the property, Arabella cleared land for construction, believing the construction was covered by an agricultural exception to the CWA. The South Carolina Department of Health and Environmental Control investigated the farm for stormwater discharges over the course of a year, and eventually the Department issued a “Notice of Violation.” Such notice is the first step in all of the Department’s enforcement proceedings; this one alleged that Arabella had violated the CWA’s prohibition on discharges into regulated waters. Later, Arabella and the Department agreed to a Consent Order, which required the farm to get a discharge permit and pay a $6,000 fine.

However, after the initial Notice but before the parties agreed to the Consent Order, Arabella received an intent-to-sue letter from a private group. Naturaland Trust, an environmental group, had sent Arabella the letter under the citizen suit provision of the CWA. Arabella challenged Naturaland’s lawsuit on procedural grounds, arguing that Naturaland’s suit was precluded by the Department’s enforcement action. The district court agreed with Arabella and determined that the Department had indeed commenced an enforcement action that precluded citizen suits. But Naturaland appealed to the Fourth Circuit, which reversed the lower court. The Fourth Circuit held that the Department’s proceeding was not sufficiently “comparable” to the federal enforcement proceeding described in the CWA, meaning Naturaland’s suit was not precluded and could proceed.

Arabella has now filed a petition asking the Supreme Court to hear its case, and the Cato Institute has joined an amicus brief filed by the Buckeye Institute supporting that petition. In the brief, we explain how the Fourth Circuit’s decision undermines the cooperative federalism that the CWA was designed to promote. The CWA encourages states to experiment with different types of enforcement actions, but the Fourth Circuit’s approach would instead require states to either enact carbon copies of the federal government’s system or permit citizen lawsuits that can compete with and undermine the state’s enforcement system. A requirement that state actions must closely mimic federal enforcement would take away states’ ability to enforce their environmental regimes as they see fit under the CWA.

The states are the primary enforcers of environmental law under the Clean Water Act, but allowing citizens to sue whenever a state proceeding does not closely mimic its federal counterpart would strip away the delicate balance between the federal and state governments. States should be free to craft their own enforcement mechanisms under the federal government’s requirements. The Supreme Court should grant review and take this case to uphold the principles of federalism under the CWA.